This invention relates in general to tool holders for cutting tools used on metal cutting lathes, and in particular to the type of tool holder which allows for easy adjustment of tool position with respect to the work to be cut.
Lathes are equipped with either a single point tool holder mounted on a compound tool rest on the carriage of the lathe or with a rotary tailstock turret which can hold several tools of various shapes and functions which can be positioned at the work either sequentially or selectively as the lathe operator chooses. Such tool holders can be made with slots and clamping bolts for holding tools with rectangular shanks, or clamps and collets for holding tools with round shanks as found with boring bars and round bars for holding cutting inserts. Many of these holders are so constructed that the tool, when clamped in the holder, is automatically on the center line of the lathe; with use, wear often causes a deterioration of the tool alignment and requires readjustment. At other times it is desirable to mount the tool either above or below the centerline of the lathe to produce the proper cutting conditions for various materials. In spite of the fact that lathes have been in use for hundreds of years, for various reasons such as convenience, economics or reliability, improvements in tool holders are still needed and therefore they are constantly being refined. For example, there have been many refinements in methods for clamping cutting tools with round shanks which use a variety of compound, eccentric collets; however, such designs tend to be expensive to manufacture because of the number of parts. Also such tool holders usually require one or more tools for adjusting the tool setting and thus are sometimes inconvenient to use.